The present invention relates to a method and device that are mainly used in the production process of semiconductor electronic circuits and are for reviewing and analyzing, on the basis of inspection information, the composition of particles and defects generated on a semiconductor wafer.
The production of semiconductor devices is configured by numerous processes. These can be broadly divided into a substrate step for creating transistor elements on a substrate and a wiring step for creating wirings that connect these elements. These steps are respectively configured by a combination of plural processes, such as a thin-film deposition process, a photo lithography process, an etching process, an impurity doping process, a anneal process, a polarization process and a cleaning process. The number of such manufacturing steps can sometimes reach several hundreds of steps.
When defects and particles are generated on a semiconductor wafer due to inadequacies or abnormalities in the production conditions of the manufacturing device, the probability that defects will be generated in the products becomes higher and results in lowering yield. Thus, inspections such as particles inspection and pattern inspection are implemented for each main process, and observation is conducted to determine whether or not manufacturing has been conducted normally. Additionally, measures are administered to corresponding devices when abnormalities arise. In this case, because it is impossible to implement inspection of all wafers for each manufacturing process because of time and energy constraints, ordinarily inspections are implemented with respect to sampled lots and wafers per step comprising several processes (process group).
Namely, as shown in FIG. 4, several of lots and wafers processed by a process group A comprising plural processes are sampled, and an inspection is conducted to determine whether or not the sampled lots and wafers are normal, i.e., to determine whether or not occurrences of defects and particles are within a normal range. When everything is normal, the routine proceeds to a step comprising a next process group B. When everything is not normal, a detailed inspection of detected defects and particles is conducted. From the results of this inspection, the production device, such as a manufacturing device, that caused the defects and particles (i.e., the problematic device) is identified from among the devices that executed the process group A, and a measure is devised with respect to the problematic device to ensure that defects and particles do not arise.
The inspection device scans the wafer surface with a laser to detect the presence of scattered light, or imports the shape of a pattern as an image and compares this with another image of the same pattern region, whereby information relating to the position and number of singularities can be obtained. Here, “singularities” refers to points outputted as points where abnormalities have been discovered by the inspection of the inspection device. Below, both particles and pattern defects will be referred to as defects.
Monitoring to determine whether or not the production devices are normal is often conducted using the number and density of defects detected by the inspection device as a management index. When the number of defects exceeds a preset standard value, it is determined whether or not an abnormality has occurred in the production device. As shown in FIG. 5, changes in a wafer map, which are position information of defects obtained from the inspection device, are studied, the defects are magnified and imaged on the basis of the wafer map information using a review device such as an optical microscope or a scanning electron microscope (referred to below as an “SEM”), detailed information such as the size, shape and texture of the defects is obtained, a detailed inspection such as composition analysis or cross-sectional observation is conducted, and the production device in which the problem occurred and the nature of the problem are identified. Then, on the basis of the result of the inspection, a measure with respect to the production device or process is conducted to prevent a drop in yield.
In recent years, on the basis of inspection data from particles inspection devices and pattern inspection devices, review devices that include the function of automatically obtaining a magnified image of particles and defects (Automatic Defect Review; referred to below as “DR”) have been developed (e.g., see JP-A-2000-30652). Methods that automatically classify acquired images (Automatic Defect Classification; referred to below as “DC”) are also known (e.g., see JP-A-8-21803).
Here, when composition analysis is implemented with respect to defects, it is necessary to reliably irradiate an energy beam for analysis on to the defects. Although designation of the irradiation position of this beam is commonly conducted with human hands, it is preferable to conduct designation automatically when the number of defects is large because it requires time. Also, the amount of time necessary for composition analysis is usually long in comparison with the amount of time necessary for the review. For this reason, sometimes the target of the composition analysis is narrowed down when the number of defects is large. Because it requires time when this narrowing-down is also conducted by human hands, it is preferable to conduct narrowing-down automatically when the number of defects is large.
With respect to this composition analysis, methods have been proposed where analysis is executed in an SEM disposed with an energy dispersive X-ray spectrometer (referred to below as an “ED”) that obtains composition information by irradiating an electron beam towards detected defects and analyzing the energy of characteristic X-rays emitted from the defects (e.g., see JP-A-8-148111 and JP-A-10-27833). Also, methods for obtaining more detailed information from the observed target, e.g., methods for obtaining a three-dimensional shape from an SEM image, are known (e.g., see JP-A-1-143127).
In order to automatic composition analysis, it is necessary to control with high precision the positions of the defects and the irradiation position of the electron beam for analysis so that the electron beam hits the defects. However, error is included in the coordinates obtained from the inspection device. A stage of the SEM on which the defect analysis targets, such as wafers and lots, are placed is moved on the basis of these coordinates for the composition analysis, whereby error is included even if the defect positions are set to coincide with the irradiation position of the electron beam. Moreover, in addition to this, a setting error is also included in the stage position of the SEM (thus, defect positions). For this reason, it is difficult to reliably irradiate the electron beam on defects of a size close to the error dimension of the stage. In the conventional examples of each of the aforementioned patent publications, consideration is not given to highly precise and efficient control methods that can reliably irradiate the electron beam on defects of this size.
Also, conditions in which the composition of defects is analyzed by the state of the number of defects and steps (size of the defects, whether the defects are present on the surface or inside, etc.) Or the material of surface films differ. However, in the aforementioned conventional examples, consideration is not given to such circumstances, and when composition analysis is automatically carried out, the same analysis conditions must be set even if there are changes in such circumstances.